A single unobtrusive product capable of protecting women against both disease and pregnancy should gain widespread acceptance. BIOTEK is investigating a new vaginal gel, which deactivates pathogens by low pH buffering. Phase I developed and studied vaginal gels containing 2 mg/ml of nonoxynol-9 along with a soluble buffer salt capable of holding the pH between 2 and 3. Studies included in vitro measurements of viscosity, viscous stability, equilibrium pH, buffer capacity, spermicidal activity, in vivo investigation of vaginal pH in sheep, vaginal irritation in rabbits, and microbiological tests on both harmless and pathogenic organisms. The gel appears to inactivate sperm, bacteria and HIV-1 virus. Phase I concluded with a successful effort to reduce rabbit vaginal irritation by replacing the thickening agent. Phase II will revise the Phase I formulation to eliminate nonoxynol-9, confirm the performance of the final formulation, prepare and fully characterize GMP gel, conduct an in vivo study in rabbits and prepare an IND for submission to the FDA shortly before a first human clinical study of this new vaginal product.